Advanced Biology

Course Overview

This course (designed for grades 11 or 12) builds on the content from the Introduction to Life Sciences courses to further extend students’ knowledge of life sciences concepts related to molecular genetics, biological evolution, and ecology.

Within the course, there are eight main themes from which to develop standards-based learning cycle lessons:

Cells and Energetics

Organic Molecules and Water

Molecular Genetics and Mechanisms of Heredity

Evolutionary Biology

Diversity of Organisms

Structure and Function in Organisms

Ecology

Human Impact on Earth’s Ecosystems

Here is an overview of each organizing theme, listing some of the key concepts that should be addressed.

Cells and Energetics

Organelles are membrane-bound subcellular structures that have a specific function within a cell. The cell nucleus, endoplasmic reticulum, Golgi apparatus, ribosomes, mitochondria, vacuoles, lysosomes, and chloroplasts are all examples of organelles. Prokaryotic cells (e.g., bacteria) are simple cells without membrane-bound organelles.

Eukaryotic cells go through a repeating five-phase sequence of growth and division.

All cells are enclosed in a plasma membrane. The plasma membrane regulates what moves in and out of a cell, helping it to maintain homeostasis. The maintenance of a relatively stable internal environment is continuously challenged by changing physical, chemical, and environmental conditions.

Organisms obtain energy from the bonds of glucose through a process known as cellular respiration. ATP, a by-product of cellular respiration, is a molecule that supplies most of the energy that drives an organism’s metabolism.

Organic Molecules and Water

The sun is the primary source of energy for life. Some organisms can photosynthesize, or convert light energy to chemical energy through the synthesis of glucose. This is the main pathway for energy and carbon to enter an ecosystem. These molecules can be used to assemble larger molecules of biological importance, including proteins, nucleic acids, carbohydrates, and lipids.

Cells use water to intake, dispose of, and transport the molecules necessary for life. Certain cellular mechanisms maintain specific water concentrations inside and outside of the cell in order to perform these functions. Water is often involved in biochemical reactions.

The energy stored in bonds between the atoms of these organic molecules can be used as sources of energy for life processes.

Variations in the arrangement of atoms and molecules form the basis of a variety of biological phenomena. Types of biochemical reactions include functional-group transfer, electron transfer, rearrangement, condensation, and cleavage. Enzymes are often involved in biochemical reactions.

Molecular Genetics and Mechanisms of Heredity

Human chromosomes consist of many genes and are made of DNA, a nucleic acid found in the nucleus of the cell. DNA directs all the activities of a cell. Meiosis is a process that produces sex cells, or gametes. Meiosis reduces the number of chromosomes from diploid to haploid.

Traits are inherited through alleles being passed in gametes from parents to offspring. Inheritance patterns can be complex, and usually do not follow the basic laws of genetics discovered by Mendel. The environment can also influence traits expressed in the phenotype.

Gene expression is a two-step process. Every cell must be able to control when particular genes are used—a process called gene regulation. Genes sometimes contain mutations, or changes in an organism’s DNA. Some mutations are harmful, some have no effect, and some are beneficial.

Most viruses have a protein sheath, or capsid, surrounding a core of nucleic acid. Viruses replicate inside a host cell by taking over a host cell’s machinery. Viruses are not considered to be living things since they need another living cell in order to reproduce.

Evolutionary Biology

Much of the history of life on Earth can be traced due to preservation of various organisms in rock layers. Using radiometric dating, scientists have divided Earth’s history into eras and periods known as the geologic timescale. Unique rock layers and fossils provide insight about the geology, weather, and life forms of each time period.

Living things have changed, or evolved, through time—and are still changing. Fossils are evidence of evolution. Evidence for evolution is also obtained by comparing embryology, homologous structures, chemical similarities, and vestigial structures.

Darwin proposed that evolution occurs via natural selection. Darwin believed the rate of evolution was steady, slow, and continuous. This model of evolution is known as gradualism. Another model, punctuated equilibrium, describes short periods of rapid change within a species that are separated by long periods of little or no change.

Diversity of Organisms

The earliest traces of life are cyanobacteria fossils in 3.5-billion-year-old rocks. Early cells were prokaryotic bacteria. As they photosynthesized, oxygen was released into the oceans and, eventually, after the ocean water was saturated with gas, into the air.

Taxonomy is the study of classifying and naming organisms. Organisms are classified into six kingdoms: Archaebacteria, Eubacteria, Protista, Fungi, Plantae, and Animalia. A kingdom is further subdivided into a phylum, class, order, family, genus, and species. Linnaeus developed a binomial nomenclature (a two-word naming system) that gives every organism its own scientific name.

A prokaryotic ancestral cell gave rise to Kingdom Archaebacteria and Eubacteria. The remaining kingdoms followed. Throughout evolutionary history there have been mass extinctions followed by episodes of rapid evolution. The mass extinction and subsequent Cambrian explosion and the extinction at the K-T boundary are examples.

Scientists agree that change within a species is caused by natural selection (called microevolution), which eventually leads to the appearance of new species and even new kingdoms of organisms. This new appearance of a species is known as macroevolution.

Structure and Function in Organisms

The reproduction, growth, and development of organisms follow patterns that allow adaptation to changing environments.

These adaptations reflect changes within an organism’s internal structure, which lead to the emergence of more advanced system functioning.

Plants and animals have a variety of built-in mechanisms that respond to various environmental conditions. These mechanisms protect the organism from predators, help regulate growth and development, and ensure that reproduction occurs.

Living things require a continuous input of energy in order to maintain their internal chemical and physical organization. If energy input ceases, such as during death, living systems rapidly disintegrate toward more disorganized states.

Ecology

Ecosystems change when significant climate changes occur or when one or more new species appear as a result of immigration or speciation.

Earth is made up of a series of interconnected systems. A change in one system affects other systems. Interactions among the Earth’s lithosphere, hydrosphere, atmosphere, and biosphere have resulted in the ongoing changes of Earth’s global system. Thermal energy transfers in the world’s oceans impact physical features (e.g., ice caps, oceanic currents, atmospheric currents) and weather patterns.

Humans live at the interface between the atmosphere driven by solar energy and the upper mantle, where convection creates changes in the Earth’s crust. At times, these normal changes can be hazardous to humans.

Birth rates, fertility rates, and death rates are affected by various environmental factors, including population density, resource use, nutritional status, and toxins.

Human Impact on Earth’s Ecosystems

Factors of human population impact natural systems such as levels of education, children in the labor force, education and employment of women, infant mortality rates, costs of raising children, birth control methods, and cultural norms.

The structure and stability of ecosystems are affected by changes in their biotic and abiotic components as a result of human activity. Biotic and abiotic global changes have occurred in the past and will continue to occur in the future.

Populations can increase through linear or exponential growth, with corresponding effects on resource use and environmental pollution. This increase in population can reach or temporarily exceed the carrying capacity of a given environment.

As societies have grown, become stable, and come to value aspects of the environment, vulnerability to natural processes of change has increased.